Cathode properties of a controlled crystallinity nano-Li1.2Cr0.4Mn0.4O2 cathode for lithium ion batteries†

Abstract

The milled-Li_1.2Cr_0.4Mn_0.4O₂ (milled-LCMO) cathode, a promising material for next-generation Li ion batteries, is prepared by dry ball-milling of layered rocksalt-type Li_1.2Cr_0.4Mn_0.4O₂ (layered-LCMO) obtained by solid-state synthesis. Despite undergoing ball-milling treatment, resulting in separation into Cr-rich and Mn-rich phases along with Li₂O, milled-LCMO still exhibited a reversible capacity of 277 mA h g⁻¹ at a rate of 16 mA g⁻¹. However, it was also revealed that its cyclability was poor due to the contribution of oxygen redox in the charging process. On the other hand, layered-LCMO exhibited better cyclability because charge and discharge reactions proceeded only through the Cr redox. The thermally treated Li_1.2Cr_0.4Mn_0.4O₂ was prepared as a cathode material that combines the favorable properties of these two materials. In fact, each thermally treated sample showed a larger reversible capacity than the layered-LCMO obtained by the solid-phase method, and the cyclability recovered as the heat treatment temperature increased.